fcos

Cosine

FCOS

Computes cosine of ST(0) (in radians).

Pseudocode Operation

ST(0) ← cos(ST(0))

Encoding

Binary Layout
D9
+0
FF
+1
 
Format Legacy
Opcode D9 FF
Extension x87 FPU

Operands

Related

More in x87 FPU

Reference

View in Intel® 64 and IA-32 Architectures SDM ↗ Intel® SDM

Instruction Forms

Opcode Instruction Op/En 64/32-bit Mode CPUID Description
D9 FF FCOS Valid Valid Replace ST(0) with its approximate cosine.

Description

Computes the approximate cosine of the source operand in register ST(0) and stores the result in ST(0). The source operand must be given in radians and must be within the range -263 to +263. The following table shows the results obtained when taking the cosine of various classes of numbers. Table 3-25. FCOS Results

ST(0) SRC ST(0) DEST

- ∞ *

- F                                              -1 to +1
- 0                                                 + 1
+ 0                                                 + 1
+ F                                               - 1 to + 1

+ ∞ * NaN NaN

Operation

IF |ST(0)| < 263
THEN
C2 := 0;
ST(0) := FCOS(ST(0)); // approximation of cosine
ELSE (* Source operand is out-of-range *)
C2 := 1;
FI;

Exceptions

Protected Mode Exceptions

#NM CR0.EM[bit 2] or CR0.TS[bit 3] = 1. #MF If there is a pending x87 FPU exception. #UD If the LOCK prefix is used.

Real-Address Mode Exceptions

Same exceptions as in protected mode.

Virtual-8086 Mode Exceptions

Same exceptions as in protected mode.

Compatibility Mode Exceptions

Same exceptions as in protected mode.

64-Bit Mode Exceptions

Same exceptions as in protected mode. FCOS-Cosine Vol. 2A 3-331